package me.zhengjie.utils;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.HashMap;
import java.util.Map;

public class DistanceUtil {

    /**
     * 计算地球上任意两点(经纬度)距离
     *
    * @param long1 第一点经度
     * @param lat1  第一点纬度
     * @param long2 第二点经度
     * @param lat2  第二点纬度
     * @return 返回距离 单位：米
     */
    public static Map<String, String> getDistance(double long1, double lat1, double long2, double lat2) {
        double a, b, R;
        R = 6378137;//地球半径
        lat1 = lat1 * Math.PI / 180.0;
        lat2 = lat2 * Math.PI / 180.0;
        a = lat1 - lat2;
        b = (long1 - long2) * Math.PI / 180.0;
        double d;
        double sa2, sb2;
        sa2 = Math.sin(a / 2.0);
        sb2 = Math.sin(b / 2.0);
        d = 2 * R * Math.asin(Math.sqrt(sa2 * sa2 + Math.cos(lat1) * Math.cos(lat2) * sb2 * sb2));

        BigDecimal meter = new BigDecimal(d).setScale(2, RoundingMode.UP);
        BigDecimal kilometer = meter.multiply(new BigDecimal("0.001")).setScale(2, RoundingMode.UP);

        Map<String, String> map = new HashMap<>();
        map.put("meter", meter.toPlainString());
        map.put("kilometer", kilometer.toPlainString());

        return map;
    }
}
